Point-scanning confocal microscopy has proven to be successful for noninvasive imaging of thin sections within thick biological samples with high resolution and contrast. It has also been widely applied in industrial inspection. Unfortunately, the speed at which images are captured using point-scanning is limited. Because of this limitation, line-scanning confocal systems have been proposed that increase the speed with which images can be acquired. Such systems have been successfully tested in industrial inspection, imaging of human tissues, and ophthalmology. Instead of scanning one point in the object at a time, one line is scanned at a time in line-scanning confocal microscopy. In addition to being fundamentally simpler and faster than point scanning, line scanning can produce lateral and axial resolutions that are comparable with those obtained using point-scanning.
Despite these advantages of line-scanning confocal microscopy, it can only be used to capture intensity information and cannot be used to capture the quantitative phase information of the optical field. This is unfortunate as such information is of great interest in industrial inspection and biomedical imaging. For example, because phase information can have much higher contrast than intensity information, phase information can be used to measure very small features of an object, such as its surface roughness. It can therefore be appreciated that it would be desirable to be able to capture both intensity and phase information using line-scanning confocal microscopy.